Question

Tính nhanh:

a) 7,5 . \(\left(\frac{-2}{5}\right).\left(-2,5\right)\)

b) ( - 50,5 ) . 8 . ( - 0,25 )

c) ( 0,125 ) . ( -3,7) . ( -2 )³

Answer 1

a)

\(7,5.\left(\frac{-2}{5}\right).\left(-2,5\right)\)

\(=7,5.\left[\left(\frac{-2}{5}\right).\left(-2,5\right)\right]\)

\(=7,5.1\)

\(=7,5\)

b) 

\(\left(-50,5\right).8.\left(-0,25\right)\)

\(=\left(-50,5\right).\left[8.\left(-0,25\right)\right]\)

\(=\left(-50,5\right).\left(-2\right)\)

\(=101\)

c)

\(\left(0,125\right).\left(-3,7\right).\left(-2\right)^3\)

\(=\left(0,125\right).\left(-3,7\right).\left(-8\right)\)

\(=\left[\left(-8\right).\left(0,125\right)\right].\left(-3,7\right)\)

\(=\left(-1\right).\left(-3,7\right)\)

\(=3,7\)

Chúc cậu học tốt !!!